Foxes are actually one of the animals that a rabbit can sometimes best in 1v1 combat in their natural setting. It has a lot to do with body weight to muscle ratio, angle of attack and weak points on the fox's hind quarters combined with his blind spots.

One famous example is when a rabbit named Peppy Hare got behind a fox named James McCloud and put a serious beating on him - it was repeated in multiple experiments in multiple settings across multiple Nintendo platforms. If you take away the space ships though the fox wins, I guess.